The invention concerns a formwork system for concrete bodies with recesses, consisting of an inner formwork, an outer formwork and an opening box-out (recessed formwork) disposed between the inner and outer formworks.
A formwork system of this type is disclosed e.g. in DE 198 00 568 C1.
The known opening box-out can be used to form an opening for a window, a door or the like in a concrete component. The opening box-out consists of reinforcing plates and side elements which, viewed in cross-section, have the shape of a T comprising a bridge and a transverse base disposed at one bridge end. The side elements can be disposed to parts of a formwork and can be connected to each other by means of reinforcing plates which can be mounted to the bridges. Reproducible shaping and mounting of the opening box-out is possible in the manner of a construction kit system with tools which are used on the building site and in a simple fashion. When the individual elements of the known opening box-out are produced from wood or a material comparable to wood, the opening box-out can be easily adapted or changed.
The depth of the known opening box-out must be permanently changed for casting concrete bodies of different thicknesses since the known opening box-out is disposed between a formwork with two heads and it must be ensured that there is no gap between the formwork shell of the inner and outer formworks and the opening box-out, into which not yet hardened concrete could flow during casting of the concrete body. The known opening box-out must be constructed, fitted and aligned between the formwork elements exactly according to the specifications. Although the known opening box-out permits lining of formwork in a relatively short time, the known opening box-out must always be newly constructed, adjusted and aligned for each recess to be produced. This requires a certain amount of time which cannot be reduced.